Power semiconductor devices may withstand a blocking voltage of up to more than 1000 Volts at high current rating. Typically, a load current through a power semiconductor device flows in a vertical direction between the two principal planes of a semiconductor body of the power semiconductor device. Gate electrodes for controlling the load current may be formed in trench gate structures extending from one of the principal planes into the semiconductor body. In common semiconductor materials such as crystalline silicon the sidewalls of the trench gate structures may be approximately vertical sidewalls. In semiconductor bodies with a main crystal direction slightly tilted to the vertical direction by on off-axis angle of some few degrees, e.g., in some silicon carbide devices, a defined tapering of the trench gate structures may compensate for the off-axis angle such that gated inversion channels can be formed in main crystal planes with high charge carrier mobility.
It is desirable to improve device characteristics and device reliability of semiconductor devices.